Term
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Definition
The purpose of the Radioactive Waste Gas System is to:
§Provide sufficient compressed nitrogen and hydrogen for filling, purging, and makeup to various components within the NSSS
§Collect, process, and reuse radioactive gases produced as a result of plant operations
§Release the accumulated gas volume from the Waste Gas System after sufficient period of decay to minimize the release of radioactive gases
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Term
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Definition
The Radioactive Waste Gas System is designed to meet the following criteria:
§To provide sufficient capacity to process and store the volume of gaseous effluent expected for a period of 45 days
§To provide cover gas for the CVCS Holdup Tanks
§To ensure that releases of radioactive gaseous wastes are kept as low as practicable
§To maintain releases below the limits set by 10CFR20
§To ensure that exposures to the public are maintained below the design objectives of 10CFR50, Appendix I
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Term
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Definition
§The Radioactive Waste Gas System has no safety-related functions and no Engineered Safety Features relative to safe shutdown of the plant
§Waste Gas System integrity must be maintained to prevent or mitigate the consequences of postulated accidents that could result in offsite doses exceeding 10CFR100 limits
§The system as a whole is classified as non-safety related
§Because they contain radioactive gases, the Waste Gas Compressors and the Decay Tanks are classified as safety related
§The Waste Gas Decay Tanks are required to withstand an Operating Basis Earthquake
§The Waste Gas System lines which penetrate containment are provided with isolation valves which automatically close upon Containment Isolation Phase A
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Term
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Definition
§Because they contain radioactive gases, the Waste Gas Compressors and the Decay Tanks are classified as safety related
•The Waste Gas Decay Tanks are required to withstand an Operating Basis Earthquake
•The Waste Gas System lines which penetrate containment are provided with isolation valves which automatically close upon Containment Isolation Phase A
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Term
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Definition
1.Degassing of the reactor coolant discharged to the CVCS and purging of the VCT prior to cold shutdown.
2.Displacement of cover gases in the following tanks:
§CVCS HUTs
§RCDT
§SRST
§PRT
§VCT
3.Discharge of Gas Analyzer
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Term
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Definition
Fission Gases:
§Primary fission gases collected in the Radioactive Waste Gas System are Xenon (Xe133) and Krypton (Kr 85)
§Largest contributor to the non-radioactive gas inventory is Helium produced by the Boron / Lithium reaction in the core and collected from the VCT cover gas. (B10(n,a)Li7)
Cover Gases:
§During normal operation the majority of the gases received by the WG system come from cover gases displaced from the CVCS HUTs as they fill with liquid.
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Term
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Definition
§One compressor is in-service in Manual
§The other is in standby (Automatic)
§Running compressor takes a suction on the vent header and discharges to the in-service GDT.
§The in-service GDT is supplying the vent header.
§If no inventory is added to any tanks then the GDT pressure should be constant with the vent header in its normal band. 2-3 psig
§If vent header pressure gets too high (>4 psig) the second, standby compressor will start.
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Term
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Definition
2WG8 maintains downstream WGC suction header pressure at 2 psig via controller PA8657.
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Term
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Definition
WG10 closes when associated WGC breaker opens.
WG10 opens when associated WGC breaker closes.
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Term
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Definition
•The normal alignment is one WGC ON and the other in AUTO
•ON: compressor runs, bypassing Vent Header pressure switch.
•AUTO: compressor runs when Vent Header pressure rises to 4 psig.
•STOP: opens breaker; prevents auto closure
•TRIPS: motor overcurrent low Separator pressure <25psig and low VH pressure 0.5 psig
•WGC Power Supply: E & G 460V
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Term
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Definition
–
Designed to hold Gas waste for 45 days
Designed to hold a full RCS Degas
0 to 110 psig
•Design Pressure
–Internal = 150 psig
–External = Atmospheric
•Relief Valve
–150 psig to the Plant Vent
•Design Temperature
–180 °F
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Term
| Waste Decay Tanks Cont... |
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Definition
•WGDT capacity permits adequate time—45 days — to allow for decay of waste gas activity prior to release based on 1% defective fuel clad and daily load reductions to 50% power for several hours.
• The basis for the 45 days is the time period to allow Xe133 (t1/2 = 5.25 days) to decay to the point where its activity is roughly the same as the Kr85 (t1/2 = 10.7 yrs) collected.
•Another criteria for the tank size, is that the tank must be capable of holding the entire contents of an RCS degas.
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Term
The purpose of the Radioactive Liquid Waste System (WL) is to:
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Definition
Ø1.Collect and process reactor-grade and nonreactor-grade liquid wastes generated during plant operation, refueling, and maintenance
Collect Equipment and Floor Drains into sumps for transfer
to the Liquid Waste System
Ø2. All liquid wastes are processed for reuse and/or discharge to the environment within the radiation limits set forth in 10CFR20
Ø3. The system is also capable of meeting the more restrictive waste discharge guidelines established by 10CFR50, Appendix I
Ø4. The system is designed to minimize exposure to plant personnel and the general public IAW Federal Regulations
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Term
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Definition
ØMaintain annual activity releases within the limits specified in 10CFR20
ØProtect the public health and safety by maintaining radioactive releases as low as practicable.
ØCollect radioactive and potentially radioactive liquid wastes
ØProvide processing of liquid wastes such that operation and availability of the stations are not limited
ØProvide appropriate holdup capacity for retention of liquid
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Term
Safety Functions:
Which valves |
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Definition
The Radioactive Liquid Waste System has no safety-related functions or ESF features, except for valves associated with Containment Isolation Phase A:
Ø WL16 & 17 - Containment Sump Pump Disch
Ø WL12 & 13 - RCDT pump Disch
Ø WL96 & 97 - RCDT sample to WGA
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WL98 & 99 - RCDT/PRT to Vent Header
Ø WL108- N2 Supply to RCDT
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Term
| Major System Storage Tanks |
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Definition
ØWaste Hold-up Tanks
ØAux Bldg Sump Tank
ØLaundry & Hot Shower / Chemical Drain Tanks
ØRCDT
ØSpent Resin Storage Tanks
ØCVCS Monitor Tanks
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Term
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Definition
ØLocated on 64 el Aux Bldg
ØDesign Press: 15 psig @180°F
ØLevel indication in the control room and at 104 pnl.
ØVented to the suction side of the Aux Bldg Exhaust Fans to maintain slight negative pressure
Ø25,000 gallon capacity
ØThe waste is processed through a Portable Demineralizer package as soon as possible to keep the tanks as empty as possible
ØIf further processing is not required, transfer can be made to either the CVCS Monitor Tanks or the Waste Monitor Holdup Tank for eventual release
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Term
| Waste Evaporator Feed Pump |
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Definition
ØUsed to move water from WHUT/WMHUT for transfers or processing
ØAlso used to recirc WHUT/WMHUT
ØCan transfer water between units! (1 way –U1 to U2 only )
ØOnly 16 gpm
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Term
| Waste Monitor Holdup Tank |
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Definition
ØFunction and design the same as WHUT
ØSizing design bases assumes an initially empty tank with:
ØApproximately 2000 cubic feet for draining the secondary side of one steam generator, or
ØApproximately 2326 cubic feet to hold one weeks worth of normal liquid waste influent
Ø3000 cubic feet is approximately 25,000 gallons
ØTwo tanks of this size provide a 100% margin
ØIncluding the Waste Monitor Holdup Tank provides 200% margin
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Term
WMHUT Pump
(Waste Monitor Hold up Tank) Pump |
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Definition
Ø60 gpm
ØControlled locally or at 104 Panel
ØPower Supply: 2E2 230V Auxiliary Building Control Center
ØLocal discharge pressure indication is provided (PL6485)
ØUsed to recirc WMHUT
ØUnit 2 only can pump directly to the CVCS Monitor Tank inlet header
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Term
Radioactive Liquid Waste Discharge Isolation Valve WL51 |
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Definition
ØOpened and closed from the control room only
ØNo automatic opening interlocks
ØWill auto close on R18 activity > setpoint
ØFails closed on loss of air, 28 and 125V DC
ØIf WL51 is open and automatically closes or fails closed (i.e., is not manually closed), the CLOSE pushbutton will flash and an audible group alarm is annunciated
Ø**Need to close on loss of CW pumps on opposite unit for dilution purposes (procedurally driven)**
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Term
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Definition
Ø2 sumps each having 2 pumps (21/22 & 23/24)
ØOne pump starts on High Level 44 inches the other on High-High 56 inches level (Off @ 30” & 48”)
ØLead pump is automatically alternated every pump down cycle
ØLocal controls only
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Term
Auxiliary Building Sump Tank
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Definition
ØLocated 51 ft el
Ø1000 gallon capacity
ØOverflow to RHR sump
ØTop portion of pipe goes to vent at the Aux Exhaust Fan via ABV Emerg Exh Hdr
ØLow elevation collection point for Aux Bldg drains that cannot drain by gravity to the WHUTs
ØLevel indicated in CR
(RP1 blue pen) and locally
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Term
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Definition
R41 RMS plant vent rad monitor, on Hi Rad Alarm, will auto Isolate WG41 (Gas Release Isolation Valve). WG 38 Gas Release Pressure Control Valve, modulates to maintain 8# for constant flow rate of 32 scfm as required by ODCM.
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Term
| What is the purpose of the WG25 and what is its set point? |
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Definition
| Separator Discharge control valve, opens at 60 psi, discharge to the in service WGDT. Ensures seal water circ through seal water heat exchanger. |
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Term
| WG Seal Water Purpose and normal operation |
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Definition
Seal water supports proper function of the WGC.
Proper level in separator is approximately WCG centerline. There is an autofill process supported by, WG 13 Separator Make up valve; WG15 Separator Drain |
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Term
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Definition
Collects RCS loop and Equipment Drains (i.e. RX Vessel Flange Leak, Accumulator Drain, Excess LTDN, etc.)
2 Pps, small (50 gpm) Large (150 gpm). At 70% lvl small Pp starts, WL12 (WL13 must be open also), At 90% the large Pp will start. At 10% lvl both Pp. stop
Interlocks-
Wl12 and WL13 both open for Pp to run, either vlv closes the Pp stop b/c don't have a recirc path.
WL12 closes at 10% RCDT lvl
To drain PRT, opening PR14 will open WL12 and start both Pp IF the WL13
Vlvs close on loss of air, power and Phase A isolation. |
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